1. Field of the Invention
The present invention relates to a liquid discharging method, a liquid jet head, and a liquid discharge apparatus for discharging a desired liquid using air bubbles created by the application of thermal energy that acts upon the liquid. More particularly, the invention relates to a liquid discharge head and a liquid discharge apparatus provided with a movable member and/or a movable separation film which is displaceable by the utilization of the air bubbles thus created.
The present invention is also applicable to a printer for recording on a recording medium, such as paper, thread, fabric, cloth, leather, plastic, glass, wood, or ceramics, as well as applicable to a copying machine, a facsimile equipment provided with communication systems, a word processor and other apparatuses having a printing unit therefor. Further, the present invention is applicable to a recording system for industrial use, which is complexly combined with various processing apparatuses.
Here, the term "recording" referred to in the description of the present invention means not only the provision of images having characters, graphics, or other meaningful representation, but also, it means the provision of those images, such as patterns, that do not present any particular meaning.
2. Related Background Art
There has been known the so-called bubble jet recording method, which is an ink jet recording method whereby to form images on a recording medium by discharging ink from discharge openings by means of acting force exerted by the change of states of ink brought about by the abrupt voluminal changes (creation of air bubbles) when thermal energy or the like is applied to ink in accordance with recording signals. For the recording apparatus that uses the bubble jet recording method, it is generally practiced, as disclosed in the specifications of U.S. Pat. No. 4,723,129 and others, that the apparatus is provided with the discharge openings that discharge ink; the ink paths conductively connected to the discharge openings; and electrothermal transducing elements arranged in each of the ink paths as means for generating energy for discharging ink.
In accordance with such recording method, it is possible to record high quality images at high speeds with a lesser amount of noises. At the same time, the head that executes this recording method makes it possible to arrange the discharge openings for discharging ink in high density, with the excellent advantage, among many others, that images are made recordable in high resolution, and that color images are easily obtainable by use of a smaller apparatus. In recent years, therefore, the bubble jet recording method is widely adopted for many kinds of office equipment, such as a printer, a copying machine, a facsimile equipment. Further, this recording method is utilized even for industrial systems, such as a textile printing, among some others.
Also, in order to obtain high quality images, there has been proposed a driving condition for the provision of a liquid discharging method or the like that may be able to execute excellent ink discharges on the basis of the stabilized air bubble creation that enables ink to be discharged at higher speeds. Also, with a view to making higher recording possible, there has been proposed an improved flow path configuration in order to obtain a liquid discharge head that may be able to perform a higher refilling of liquid at each time liquid is discharged. One example of such proposal is disclosed in the specification of Japanese Patent Application Laid-open No. 63-199972. The invention thus disclosed is such that the backwaves, which are generated along the creation of the air bubble (the pressure exerted in the opposite direction of the discharge opening, that is, the pressure directed to the liquid chamber 1012), are arranged to reside in the initial position which is away from the air bubble creation area formed by each of the heat generating devices. Then, the valve, which is positioned on the side opposite to the discharge opening with respect to the heat generating device, is postured as if to attach to the ceiling by the presence of such backwaves. This valve is then allowed to hand down into the flow path along with the creation of each of the air bubbles. This invention is to suppress the energy loss by controlling part of such backwaves by use of the valve in such a manner as disclosed in the specification of the above-mentioned application.
On the other hand, there have been disclosed in the specifications of Japanese Patent Application Laid-open No. 61-69467, Japanese Patent Application Laid-open No. 55-81172, and U.S. Pat. No. 4,480,259, among some others, a method for discharging liquid by enabling the pressure exerted by bubble generation to be carried over to the discharge liquid, while arranging to make use of the liquid (bubble generating liquid) that creates air bubbles by the application of heat, and the liquid that performs discharging (discharge liquid) separately. In the specification of these publications, the ink that serves as the discharge liquid and the bubble generating liquid are completely separated by means of a movable separation film formed by silicone rubber or the like. Thus, the discharge liquid is not allowed to contact the heat generating devices directly. Here, at the same time, the structure is arranged so that the pressure exerted by the bubbke generation of the bubble generating liquid is carried over to the discharge liquid by utilizing the deformation of the movable separation film. With structure thus arranged, it is attainable to prevent the deposit from being accumulated on the surface of each of the heat generating devices, as well as to make the selection of discharge liquids more freely.
In addition, the structure that uses a large film for separating the entire body of a head into the upper part and lower part thereof is disclosed in the specification of Japanese Patent Application Laid-open No. 59-26270. The large film thus disclosed is nipped aby the two plate members that form liquid flow paths. The plate members are provided for the purpose of preventing liquids from being mixed with each other in the two flow paths thus provided.
Also, there is disclosed in Japanese Patent Application Laid-open No. 5-229122 the structure under which, while providing special features for a bubble generating liquid itself, this liquid is used at a lower boiling point than that of a discharge liquid in order to maintain the bubble generation characteristics of such liquid. There is also the structure that uses a conductive liquid as a bubble generating liquid as disclosed in Japanese Patent Application Laid-open No. 4-329148.
However, since the head that separates the discharge liquid and the bubble generating liquid completely as described above is structured to carry over the pressure exerted at the time of bubble generationto the discharge liquid by means of the deformation of the movable separation film that may result from its expansion, a considerable amount of bubble generation pressure is absorbed by the movable separation film eventually. Also, the amount of deformation cannot be made larger enough. Therefore, although it is possible to separate the discharge liquid and the bubble generating liquid, there is a possibility that the energy efficiency and the discharge force are made lower after all.